1. Scope

1.1 This test method is intended to measure shrinkage from mold cavity to molded dimensions of thermosetting plastics when molded by compression, injection, or transfer under specified conditions.

1.2 This test method provides for the measurement of shrinkage of thermosetting plastics from their molds both initially (within 16 to 72 h of molding) and as they age (post-shrinkage at elevated temperatures).

1.3 This method will give comparable data based on standard specimens and can not predict absolute values in actual molded parts with varying flow paths, wall thicknesses, pressure gradiants and process conditions. Differences in mold shrinkage generally is observed between the specimen geometries described in this test method.

1.4 Knowledge of the initial shrinkage of plastics is important for the construction of molds and knowledge of post molding shrinkage is important for determining the suitability of the molding material for manufacturing thermosetting plastic components with accurate dimensions.

1.5 The values stated in SI units are to be regarded as the standard. The values given in brackets are for information only.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Note 1This test method and ISO 2577-1984 are equivalent when bars of 120 mm length, 15 mm width, and 10 mm thickness are used for compression molding; or flat, square plaques approximately 120 by 120 by 4 mm are used for injection molding.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

D618 Practice for Conditioning Plastics for Testing

D796 Practice for Compression Molding Test Specimens of Phenolic Molding Compounds

D883 Terminology Relating to Plastics

D1896 Practice for Transfer Molding Test Specimens of Thermosetting Compounds

D3419 Practice for In-Line Screw-Injection Molding Test Specimens From Thermosetting Compounds

D5224 Practice for Compression Molding Test Specimens of Thermosetting Molding Compounds

E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

Keywords

molding shrinkage; post-molding shrinkage; thermoset plastics;

ICS Code

ICS Number Code 83.080.10 (Thermosetting materials)

DOI: 10.1520/D6289-03

ASTM International is a member of CrossRef.